The investigation is ongoing, but State Police said it ­appeared that the bus rear-ended a vehicle stopped at a traffic light, pushing the first car into a second vehicle also stopped at the traffic light.

No citations have been ­issued, State Police said.

At Newton-Wellesley Hospital Tuesday, the mother of a Metco student rushed into the emergency room to be with her daughter.

She and another woman ­arrived at Newton-Wellesley around 10:30 a.m., walking briskly with concerned expressions on their faces.

“She just got her nose bruised, but she’s fine,” said the mother, who declined to provide her name. “I’m just concerned right now about my child’s welfare.”

The two women spent about 30 minutes inside the emergency room before emerging with the woman’s daughter.

Some students were taken to Beth Israel Deaconess Medical Center with minor injuries, a spokesman said.

Carol A. Pilarski, Lexington’s assistant school superintendent, said in a statement that a bus monitor and the driver were not taken to the hospital.

“It appears that none of the students or staff on the bus were seriously injured, though 11 have complained of neck or head pain,” Pilarski said.

The school system said that the parents of all 34 students had been contacted and that officials would release a thorough accident report from Newton police when it becomes available.

The bus was carrying students to the Jonas Clarke and William Diamond middle schools in Lexington,
officials said.

Metco, a voluntary program founded in 1966, sends 3,300 children from Boston and Springfield to suburban school systems.